During a gyroscope startup, the gyroscope motor takes a finite time to reach full steady state amplitude. During this time, rate estimates (if needed) are generally not accurate. Rate sensing with gyroscopes, such as a tuning fork gyroscope, have been largely avoided with current methods until the gyroscope motor is up and running in a steady state fashion.
In a tuning fork gyroscope, the sensed rate is proportional to the peak-to-peak amplitude of the oscillating proof-mass. Since this amplitude starts at zero (prior to power being applied) and then grows to final steady state amplitude over a period of time during startup, sensing rate during this time has not been feasible. Rather, sensing rate has been limited to periods after steady state motor amplitude is achieved.
Delays in achievable rate sensing from time of power application can be significant, depending upon how long it takes for the gyroscope motor to achieve full amplitude. Some gyroscope applications call for accurate performance very shortly after activation. For example, current tuning fork gyroscope devices such as those used in inertial measurement units (IMUs) and rate sensors can take approximately 0.4 to 3 seconds to reach accurate rate sensing operation. This delay can be intolerable for highly accurate guidance applications that require rate sensing information at the earliest possible point after power application.